.shadow {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background-color: rgba(0, 0, 0, 0.3);
}

.center {
  width: 400px;
  background-color: #fff;
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  padding: 15px;
}

header {
  height: 40px;
  line-height: 40px;
  border-bottom: 1px solid #000;
}

footer {
  border-top: 1px solid #000;
  display: flex;
  justify-content: flex-end;
  padding: 20px 0 0;
}
